This study is to assess the efficacy of treatment with misoprostil to inhibit episodes of systemic mastocyte activation in patients with idiopathic anaphylactoid attacks, aspirin-induced anaphylactoid attacks, and systemic mastocytosis. This has been a long-term on going study which we continue to track the patients. It is hopeful that with such long term tracking, new treatment regimen will be developed for these patients.